AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

Why does Aviation Fuel contain lead?

Lead is an important raw material in producing numerous essentials, ranging in application from manufacturing car batteries to producing aviation fuel. Its malleability, anti-knock properties, high density, low melting point, flexibility, and relative inertness to oxidation make it very useful. It is also extensively used in construction, batteries, weights, fusible alloys, white paints, leaded gasoline, and radiation shielding.

Though lead is widely used, the element's toxicity is a well-known fact. Lead in all forms is a toxic substance that can cause adverse effects on humans and the environment. However, lead is used in aviation fuel because of its properties which are necessary for the efficient combustion of fuel.

Benefits of Using Lead in Aviation Fuel

Lead is malleable, ductile, dense, and a poor conductor of electricity. Nevertheless, it is a critical additive in aviation fuel. Listed below are the benefits of using lead in aviation fuel:

  • Octane rating enhancement: The octane rating measures how well a fuel performs when burned in a combustion chamber, and octane is critical for the safe running of a plane or car engine. Tetraethyl lead (TEL) is a lead-based additive used in aviation fuel to improve or increase octane ratings. High-performance engines allow airplanes to travel faster and carry more cargo, but they require higher-octane aviation fuel. Operating aviation or automotive piston engines on fuel with lower octane ratings than their minimum requirements may result in knock damage. However, it is generally safe to operate piston engines on fuel with higher octane ratings than their minimum requirements.
  • Combustion regulation: Lead's presence in aviation fuel allows it to function as a combustion decelerator. Lead prevents the fuel-air mixture in the combustion chamber from igniting prematurely.
  • Efficient combustion of fuel: Because lead (TEL) in aviation fuel has a slower combustion rate, the fuel expands more during ignition, resulting in smoother and more efficient combustion.
  • Anti-explosion: Aviation fuel can still be prematurely ignited in the combustion chamber and explode due to contaminants. In the event of pre-ignition, lead acts as a shield and anti-explosion agent. This benefit aids in the prevention of engine damage.
  • Engine cycle efficiency: The presence of lead in aviation fuel increases its useful compression ratio or supercharger ratio. It will further lead to a more efficient engine cycle.

Adverse Effects of Using Lead in Aviation Fuel

While lead is widely used in many components, all forms of lead are toxic. If inhaled or swallowed, all types of lead are hazardous. Lead has a variety of consequences on human health, including effects on the brain system, red blood cells, the cardiovascular system, and immune system. Lead can also cause behavioral and learning issues in infants, preterm births, and reduced IQs. Because of their developing neurological systems, children are more sensitive to lead.

The use of leaded fuel is continued in aviation because, without the additive TEL, the octane levels in some engines would be low. As lower octane fuel will result in engine failure, TEL is not prohibited in aviation fuel.

Types of Aviation Fuels

Commercial airplanes, private jets, and general aviation aircraft widely use and depend on two main types of airplane fuel: Jet Fuel and AVGAS.

Jet fuels are hydrocarbon-rich kerosene-based fuels with high enough octane ratings to run compression and turbine engines. Because they already have a high enough octane rating to enable efficient combustion in combustion chambers, this aviation fuel type does not require lead additions. Despite being more unstable than AVGAS, its combustion efficiency makes jet fuel excellent for large commercial flights.

In contrast, AVGAS is a gasoline-based fuel. Consequently, the octane rating of gasoline is low on its own. On the other hand, AVGAS has a higher octane rating than regular automobile gasoline due to the addition of TEL. In addition, the presence of lead gives it anti-knock qualities, making it a stable and reliable fuel.


Lead is a vital additive to aviation fuel. Although aviation engineers believe that lead is harmful, there are several evident benefits lead provides in aviation gasoline. Fastener Orbit is a leading aviation parts, NSN parts, and fastener fuel cell distributor. If you want efficient aviation parts for your aircraft, look no further than Fastener Orbit. We leverage quick shipping times with affordable prices. We guarantee quality aircraft products with full time customer support. 


February 19, 2023
December 2, 2022

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